Abstract
Determining the degree of oil water encroachment is crucial for setting an appropriate operating regime of gathering and transportation pipelines, improving the efficiency of technological processes, and mitigating negative environmental impacts. This study investigates the effect of oil encroachment degree on the component composition of dissolved gas under static conditions in water-liquid-hydrocarbon systems with different volume ratios at various pressures. Experiments were carried out in a high-pressure bomb (PVT) using dodecane as an oil model and natural gas of known composition as the gas phase, followed by chromatographic analysis of produced gas samples. The results processed by expert assessment demonstrate a regular influence of water encroachment degree on the content of individual gas components, which made it possible to construct a classification function for diagnosing the encroachment regime. It is shown that an increase in the water phase fraction in the oil-water-gas system leads to a redistribution of hydrocarbon and non-hydrocarbon components between phases and to noticeable changes in gas saturation and saturation pressure. The obtained dependences enable resource-saving diagnostics of oil encroachment based on gas composition dynamics in field gathering systems, reducing energy consumption and preventing complications during multiphase pipeline transportation. Bibl. 32, Tab. 2, Fig. 3.